In the manufacture of semiconductor devices, an electrolytic plating apparatus is used to deposit a metal (e.g., copper) on a substrate, such as a wafer. Generally, the electrolytic plating apparatus is configured to plate a substrate by immersing a substrate holder that is holding the substrate, to be plated, in a plating solution held in a plating tank and applying a voltage between an anode and the substrate. A feeding terminal is connected to a wire that is connected to a negative pole of a power supply, and the substrate holder has an external electric contact that is to be electrically connected to the feeding terminal. The substrate holder further has an internal electric contact which is to be held in contact with a conductive layer (e.g., a seed layer) of the substrate.
When the substrate is held by the substrate holder, the internal electric contact is brought into contact with the conductive layer of the substrate, so that the substrate is electrically connected to the substrate holder. Further, when the substrate holder is placed on the plating tank, the external electric contact of the substrate holder is brought into contact with the feeding terminal, so that the substrate holder is electrically connected to the negative pole of the power supply. The substrate is electrically connected to the negative pole of the power supply through the substrate holder, and therefore the power supply can apply a voltage between the anode and the substrate.
Each of the above-discussed electric contacts is formed by a thin metal plate and is of a rectangular shape for easy contact with the feeding terminal or the substrate. Therefore, when an excessive force is exerted on the electric contact, it may be deformed or may be, in some cases, broken. Moreover, repetitive use of the substrate holder may cause the electric contacts to be broken due to fatigue. Furthermore, the electric contacts are expensive because the metal plates of the electric contacts are plated with gold for increased electric conductivity.